Casino House Edge 101: What Is It and How to Calculate It?

The house edge is the mathematical advantage a casino holds over players on every bet, expressed as a percentage of each wager the casino expects to keep over time. Blackjack with basic strategy has one of the lowest house edges at 0.5%, while American roulette sits at 5.26% and some slot machines can reach 10% or higher. Understanding these numbers is the single most useful thing you can do before sitting down at any casino table or spinning any reel — it tells you exactly how much the math is working against you, and which games give you the best shot at walking away ahead.

What Is the Casino House Edge?

The house edge is the built-in profit margin that every casino game carries, representing the percentage of each bet that the casino expects to keep over thousands of hands, spins, or rolls. If a game has a 2% house edge, the casino keeps an average of $2 for every $100 wagered — not per session, but across the long run of all bets placed on that game.

Think of it like this: the house edge is the price of admission to play. Every game is designed so the payouts are slightly less than the true odds of winning. That gap between true odds and payout odds is where casinos make their money. They don’t need to cheat, rig outcomes, or manipulate results. The math does the work for them, 24 hours a day.

A 0.5% house edge on blackjack means the casino expects to earn 50 cents for every $100 you wager over time. A 5.26% edge on American roulette means they expect $5.26 per $100. Those fractions might sound small, but multiply them by thousands of players making thousands of bets per day, and you start to see why online casinos and their brick-and-mortar counterparts are billion-dollar businesses.

How to Calculate the House Edge

You calculate the house edge by comparing what a bet actually pays versus what it would pay at true odds. The formula is straightforward: subtract the expected return from the total amount wagered, then divide by the amount wagered. Three worked examples make this concrete.

American Roulette: Single Number Bet

An American roulette wheel has 38 pockets: numbers 1 through 36, plus 0 and 00. When you bet on a single number, the true odds of hitting it are 37-to-1 (37 losing pockets for every 1 winner). But the casino pays only 35-to-1.

• You bet $1 on number 17. There are 38 possible outcomes.
• If you win (1/38 chance), you receive $36 total ($35 profit + your $1 back).
• If you lose (37/38 chance), you lose $1.
• Expected value: (1/38 x $35) – (37/38 x $1) = $0.921 – $0.974 = -$0.053
• House edge: $0.053 / $1 = 5.26%

That 5.26% applies to nearly every bet on the American roulette layout — red/black, odd/even, columns, dozens. The one exception is the five-number bet (0, 00, 1, 2, 3), which bumps the edge up to 7.89%. Experienced players call it the “sucker bet” for a reason.

European Roulette: Single Number Bet

European roulette uses a 37-pocket wheel with only a single 0 (no 00). That one missing pocket cuts the house edge nearly in half.

• True odds: 36-to-1. Payout: still 35-to-1.
• Expected value: (1/37 x $35) – (36/37 x $1) = $0.946 – $0.973 = -$0.027
• House edge: 2.70%

Same game, same rules, same payouts — but one fewer pocket drops the edge from 5.26% to 2.70%. If you have the choice between American and European roulette (and many online casino platforms offer both), always pick European.

Blackjack: Basic Strategy

Blackjack is more complex because player decisions affect the outcome. With perfect basic strategy (hitting, standing, doubling, and splitting at the mathematically optimal times), the house edge on a standard 6-deck shoe drops to roughly 0.5%. Play by gut instead of strategy, and that number can climb to 2% or higher — which is why learning basic strategy is worth your time before you sit down at any table.

House Edge by Casino Game

Not all casino games are created equal, and the house edge varies dramatically from one game to the next. The table below covers the most common games you’ll find at both online and land-based casinos, ranked from lowest to highest edge. These numbers assume optimal play where strategy is involved.

The spread in that table tells the whole story. A blackjack player using basic strategy faces a 0.5% edge. A keno player faces 25% or more. Over 1,000 bets of $10 each, the blackjack player loses an expected $50. The keno player? $2,500. Same total wagered, wildly different outcomes.

Why the House Edge Matters for Your Bankroll

The house edge directly determines how fast your bankroll erodes during a typical session. A lower edge means your money lasts longer, you get more playing time for the same budget, and your chances of ending a session ahead improve significantly — even though the casino still holds the long-term advantage.

Here’s a practical example. Say you bring $500 to the casino and make $10 bets. You play for four hours and average about 60 bets per hour, putting a total of $2,400 through the game.

• Blackjack (0.5% edge): Expected loss = $12. You’d likely leave with most of your bankroll intact.
• American Roulette (5.26% edge): Expected loss = $126. A noticeable dent.
• Slots (8% edge, 600 spins/hour): At 600 spins x 4 hours x $1 = $2,400 wagered. Expected loss = $192.

Those numbers assume average luck — no hot streaks, no cold streaks, just the math playing out. In reality, variance means your actual results will swing above and below those expected losses. But over time, the house edge is an anchor that always pulls your results toward it. The lower the edge, the more room variance has to work in your favor.

House Edge vs. Return to Player (RTP)

RTP (Return to Player) is simply the house edge flipped to the player’s perspective. If a slot machine has a 4% house edge, its RTP is 96%. If blackjack has a 0.5% edge, its RTP is 99.5%. The two numbers always add up to 100%.

You’ll see RTP used most often with slot machines, where online slots and progressive jackpots typically list their RTP in the game rules or paytable. Table games more commonly reference house edge. Either way, the math is the same — you just need to know which direction the number runs.

One important caveat: RTP is calculated over millions of spins or hands. In a single session of 200 spins, your actual return could be anywhere from 0% to 500% or more. RTP and house edge describe the long-term gravitational pull, not what happens on any given night.

Which Casino Games Have the Lowest House Edge?

Blackjack, baccarat, and craps consistently offer the lowest house edges in any casino, making them the best choices for players who want to maximize their playing time and minimize expected losses. But the specific bet within each game matters as much as the game itself.

Blackjack: 0.5% With Basic Strategy

Blackjack’s edge drops to 0.5% or lower when you follow basic strategy — a set of mathematically proven decisions for every possible hand combination. Basic strategy charts are freely available online and legal to use at most casinos (some even sell laminated cards in the gift shop). The key rules that push the edge lowest include 3:2 payouts on natural blackjack, the ability to double down, and liberal splitting rules. Watch out for 6:5 blackjack tables, which nearly triple the house edge to around 1.4%.

Baccarat: 1.06% on Banker

Baccarat requires zero skill or strategy — you just pick banker, player, or tie. The banker bet carries a 1.06% edge (after the 5% commission on wins), and the player bet sits at 1.24%. The tie bet? That jumps to 14.36%, which is why serious baccarat players pretend it doesn’t exist.

Craps: 1.36-1.41% on Pass/Don’t Pass

The pass line bet at 1.41% and don’t pass at 1.36% are among the best bets in any casino. Even better, craps lets you back those bets with “odds” — a unique wager that pays at true odds with zero house edge. Taking maximum odds behind a pass line bet can bring the combined edge below 0.5%, depending on the table’s odds limits.

Which Casino Games Have the Highest House Edge?

Keno, the Big Six Wheel, and certain side bets carry the highest house edges in the casino — often 10% or more, with some exceeding 25%. These games trade favorable math for simplicity and the chance at outsized payouts.

Keno is the most extreme example. With a house edge of 25-29%, a $1 keno player wagering 20 times per hour loses an expected $5-6 per hour. That might sound manageable until you compare it to the $0.30 per hour a blackjack player loses at a $10 table with basic strategy. Keno can be fun as an occasional lottery-style diversion, but it’s not a game to grind.

The Big Six Wheel (also called the Wheel of Fortune or Money Wheel) sits in the 11-24% range depending on which segment you bet. It’s positioned near casino entrances because it’s eye-catching and easy to understand, but the math is harsh. Experienced players walk right past it.

Can You Beat the House Edge?

In pure games of chance like roulette and slots, no — the house edge is baked into the math and no strategy can overcome it. But a handful of scenarios exist where skilled players can tilt the odds, or where external factors temporarily erase the edge. Here’s a breakdown of whether beating the house is really possible.

Card Counting in Blackjack

Card counting is the most well-known advantage play technique. By tracking the ratio of high cards to low cards remaining in the shoe, a counter can identify situations where the odds temporarily shift in the player’s favor and bet more during those windows. It’s legal but casinos can (and do) ask counters to leave. The edge a skilled counter gains is typically 0.5-1.5% — real, but modest, and it requires significant practice and discipline.

Poker: Playing Against Other Players

In poker, you’re not playing against the house — you’re playing against other players, and the casino takes a small percentage (the rake) from each pot. A skilled poker player can absolutely earn a long-term profit because the edge comes from outplaying opponents, not from the game’s mathematical structure. The rake is typically 2.5-5% of the pot, capped at a fixed amount.

Bonus Hunting and Promotions

Casino bonuses can temporarily flip the math. If an online casino offers a $500 deposit match with a 20x wagering requirement (T&Cs apply), you need to wager $10,000 before withdrawing. Playing that through on blackjack at 0.5% edge costs an expected $50, netting you $450 in theoretical profit. That’s a real edge — though casinos have gotten much better at structuring terms to limit this advantage.

Common House Edge Myths

Several persistent myths about the house edge lead players to make worse decisions at the table. Here are the biggest misconceptions and why they’re wrong.

“I’m due for a win.” This is the gambler’s fallacy — the belief that past results influence future outcomes on independent events. If a roulette ball has landed on black 10 times in a row, the probability of the next spin being red is still 47.4% on an American wheel. The ball doesn’t have a memory, and neither does the wheel.

“The house edge means I’ll lose exactly that percentage every time.” Not even close. The house edge is a long-term average across millions of outcomes. In a single session of 100 hands, your results will vary wildly from the expected value. You might win 60% of your blackjack hands one night and 35% the next. The edge is about gravitational pull, not a fixed deduction from every bet.

“Online casino games have a higher house edge than physical casinos.” Generally the opposite is true. Online casinos have lower overhead costs (no floor staff, no physical building, no free drinks), which allows many to offer games with lower edges. According to research published by the UNLV Center for Gaming Research, online slots frequently offer RTP values of 95-97%, compared to 88-93% at many land-based casinos.

“Betting systems can overcome the house edge.” No betting system — Martingale, Fibonacci, D’Alembert, or any other — can change the underlying mathematics. Doubling your bet after every loss (Martingale) doesn’t reduce the house edge; it just concentrates your risk into fewer, larger swings. You’ll win more sessions, but the sessions you lose will be catastrophic.

How to Use House Edge Data to Make Smarter Bets

Knowing the house edge for every game on the floor gives you a decision-making framework that most casual players lack. Here’s how to put that knowledge to work in practical terms.

Pick your games by the numbers. If you’re choosing between American roulette (5.26%) and European roulette (2.70%), the choice is obvious. If you’re deciding between Caribbean Stud (5.22%) and blackjack with basic strategy (0.5%), that’s a 10x difference in expected cost per hour of play. Let the math guide you.

Set a bankroll based on expected loss. If you want to play for four hours and your expected loss rate is $15/hour, bring at least $200-250 to cover variance and give yourself a realistic shot at a full session. Underfunded sessions end early and frustrate, even when you’re playing the right games.

• Learn basic strategy for skill-based games. The gap between optimal and suboptimal play in blackjack is roughly 1.5% — the difference between a 0.5% edge and a 2% edge. That’s an extra $15 per hour at a $10 table. Free basic strategy trainers exist online; 30 minutes of practice pays for itself quickly.
• Avoid side bets and novelty games. The base game almost always has a lower edge than any side bet attached to it. Stick to the core wager.
• Read the rules before you sit down. Small rule changes affect the edge. A blackjack table paying 6:5 instead of 3:2 on naturals increases the edge by about 1.4%. A craps table offering 10x odds behind the pass line brings the combined edge below 0.2%.
• Track your play. Keep a simple log of games played, time spent, and results. Over time, you’ll see your actual results converge toward the expected loss predicted by the house edge — and you’ll develop a much more realistic understanding of your true cost of play.

The house edge isn’t something to fear or try to outsmart. It’s information — and informed players make better choices about where to spend their time and money. Every casino game is designed to produce a profit for the house over the long run. But the difference between a 0.5% edge and a 25% edge is enormous, and choosing the right games is the most impactful decision you’ll make on any casino visit. For more on which games give skilled players the best shot, see our guide to the most profitable casino games for skilled players.

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